1. Field of the Invention
This invention relates to a discharge liquid agitating mechanism in an inkjet recording apparatus which records images on a recording medium in an inkjet mode, and to an inkjet recording apparatus having the discharge liquid agitating mechanism.
2. Description of the Related Art
In such an inkjet recording apparatus, pigment ink, or UV (Ultraviolet) ink mixed with a curing accelerator or a UV curable resin, is used as a discharge liquid for recording images on a recording medium. The UV ink is cured by being irradiated with ultraviolet light from a UV lamp immediately after the ink is discharged to the recording medium. Therefore, by using such UV ink, it is possible to perform proper printing not only on ordinary paper but also on a film made of a resin which does not absorb ink.
Such UV ink has a problem that pigments acting as a coloring material, metal particles for giving a special gloss and other contained particles settle in the interiors of ink tanks and ink supply routes. An uneven concentration distribution of these particles inside the ink tanks not only causes a reduction in printing accuracy, but can also cause an unsatisfactory discharge performance of inkjet heads when the inkjet recording apparatus is not used for a certain period of time.
Under the circumstances, an inkjet recording apparatus described in Japanese Unexamined Patent Publication No. 2006-327048 has main tanks and subtanks, and uses a pump to circulate ink through pipelines extending between the tanks, thereby to prevent sedimentation of particles and the like contained in the ink.
However, UV curable resin contained in the UV ink, generally, is highly corrosive. Therefore, where the construction described in Japanese Unexamined Patent Publication No. 2006-327048 is employed, it is necessary to use an expensive, corrosion-resistant pump, which poses a problem that the entire apparatus becomes expensive.